The present invention relates to hydrosilation reactions and more particularly the present invention relates to the production of zero valent nickel complexes as catalysts for hydrosilation reactions.
Hydrosilation reactions have been known for a long time in silicone chemistry. Basically, such reactions comprise reacting a hydrogen-containing silane with an olefinic compound so as to add the hydrogen and silicon onto the olefinic group and form the desired compound. A more important role for such reactions has been to produce silicone elastomers. Such compositions comprise the utilization of a vinyl-terminated polysiloxane polymer in combination with a hydride-containing siloxane in the presence of a platinum catalyst to produce either at room temperature or at elevated temperatures a silicone elastomer. In such compositions, it was generally the practice to package the platinum catalyst with the vinyl siloxane but separate from the hydride siloxane. When it was desired to cure the composition, the two packages were mixed without an inhibitor and cured at room temperature to a silicone elastomer. Sometimes an inhibitor such as an alkenyl maleate, a hydroperoxide-containing compound or other well known inhibitor was utilized to extend the work life of the composition or to make it a one-package composition. By utilizing an inhibitor the composition could stay in the mixed state without curing at room temperature. However, upon being heated at an elevated temperature, that is a temperature above 100.degree. C., the composition would cure to a silicone elastomer.
It was also the practice to incorporate various other ingredients such as, for instance, vinyl-containing resins composed of monofunctional siloxy units, tetrafunctional siloxy units and difunctional siloxy units. It was the purpose to utilize such vinyl-containing resins in such compositions as disclosed above to add to the strength of the cured composition without unduly increasing the uncured viscosity of the composition. It should be noted that such compositions are referred to in simple terms as SiH Olefin platinum catalyzed compositions. An example of such a composition is, for instance, to be found in Modic U.S. Pat. No. 3,436,366 which is hereby incorporated by reference. Note that in addition to the vinyl containing resins there may be utilized fillers. Reinforcing fillers such as fumed or precipitated silica or various types of extending fillers may be utilized whether treated or untreated as disclosed in Jeram U.S. Pat. No. 4,041,010 which is hereby incorporated by reference. As noted in the foregoing Jeram patent, the composition may contain fluorine substituent groups in the basic vinyl-containing polymer as well as the hydride cross-linking agent. The fluorine substituent groups give the composition exceptional solvent resistance.
As disclosed in the foregoing Jeram patent a hydrosiloxane cross-linking agent may be composed of various types of hydrides. Accordingly, there may be utilized as a cross-linking agent a hydride-containing resin composed of hydride-containing monofunctional siloxy units, and tetrafunctional siloxy units or a hydride-containing resin composed of hydride-containing monofunctional siloxy units, tetrafunctional siloxy units, and difunctional siloxy units. As noted in the foregoing Jeram patent, it was common to utilize many types of platinum catalysts in such reactions such as, for instance, from 1 to 100 ppm of the total composition could be a platinum catalyst wherein the platinum catalyst could be utilized as platinum deposited on solid carriers such as platinum on charcoal, or platinum on gamma-alumina or perhaps a solubilized platinum complex. A solubilized platinum complex was preferred in that the composition was more reactive. Accordingly, as disclosed in the foregoing Jeram patent, preferred platinum catalysts are those platinum compound catalysts which are soluble in the reaction mixture. The preferred platinum compounds can be selected from those having the formula EQU (PtCl.sub.2.Olefin).sub.2
and EQU H(PtCl.sub.3.Olefin)
as described in U.S. Pat. No. 3,159,601, Ashby. The olefin shown in the previous two formulas can also be any type of olefin but preferably is an alkenylene having 2 to 8 carbon atoms, a cycloalkenylene having 5 to 7 carbon atoms or styrene. Specific olefins that may be utilized in the above formulas are ethylene, propylene, the various isomers of butylene, octylene, cyclopentene, cyclohexene, cycloheptane, and so forth. A further platinum material usable in the composition of the present invention is the chloride cyclopropane complex (PtCl.sub.2.C.sub.3 H.sub.6).sub.2 described in U.S. Pat. No. 3,159,662, Ashby.
Still, further, the platinum containing material can be a complex formed from chloroplatinic acid with up to 2 moles of acid per gram atom of platinum of a member selected from the class consisting of alcohols, ethers, aldehydes and mixtures of the above as described in U.S. Pat. No. 3,220,972, Lamoreaux.
Another preferred platinum catalyst that may be utilized because of its higher reactivity is that disclosed in Karstedt U.S. Pat. No. 3,715,334. Generally speaking, this type of platinum complex is formed by reacting chloroplatinic acid containing 4 moles of water of hydration with tetravinylcyclotetrasiloxane in the presence of sodium bicarbonate in an ethanol solution.
Any type of platinum catalyst may be utilized in these reactions. However, the solubilized platinum complex catalyst as disclosed above such as the Karstedt and Lamoreaux catalyst are the preferred ones because of the high reactivity in promoting the addition reaction of the hydride to the vinylsiloxane.
The difference between two types of reactions in the instant case must be noted, that is, one wherein the hydride silane or siloxane adds on to an olefinic-containing compound which may be an organic compound to produce an intermediate compound which may be utilized in various types of processes or reactions. However, the other important type of reaction is the reaction of a hydrosiloxane resin or hydride-containing polysiloxane as disclosed in the foregoing Jeram patent in combination with a vinyl-containing polysiloxane to produce a silicone elastomer either at room temperature or elevated temperatures. Such compositions can be utilized to produce molds, gasketing material, various types of fabricated products, etc.
By far the main catalyst that has been utilized in such reactions is a platinum catalyst. It should be noted that palladium and rhodium can also be utilized as a catalyst in such reactions but their costs are at least as high as the platinum. Accordingly, it is highly desirable to find a low cost catalyst for such reactions.
The complex bis(1,5 cyclo-octadienyl)nickel hereinafter called Ni(COD).sub.2 has been used as a soluble catalyst precursor for a variety of alkene transformations including polymerization as disclosed in P. W. Jolly and G. Wilkey, The Organic Chemistry of Nickel, Vol. II, Academic Press, New York, 1975, p 6; H. Takaya, M. Yamakawa, and R. Noyori, Chem. Lett. (1973) 781; M. Capka, Chem. Prum., 26 (1976) 522; and M. Capka and V. Macho, Czech. Patent 174,585. Such a catalyst has also been known for hydrosilation reactions, that is, adding a hydrogen containing silane onto an olefinic group of organic compounds as disclosed in the above references. However, the catalyst Ni(COD).sub.2, as far as has been known, has never been disclosed to be effective as a catalyst in the addition of a hydrosiloxane to a vinyl-containing polysiloxane.
It has unexpectedly been found that such a material is effective in an anaerobic system for the production of silicone elastomers. It has also been unexpectedly found that various types of phosphine nickel complex catalysts are effective as anaerobic catalysts in the addition of hydride groups to olefinic groups in organic compounds or olefinic containing polysiloxane compounds. In the case where the nickel phosphine complex compounds are utilized as catalysts to react hydride-containing siloxanes with olefinic containing polysiloxanes, there results a silicone elastomer.
It is one object of the present invention to provide nickel complex catalysts for anaerobic systems in which hydrogen-containing silanes and hydrogen containing siloxanes are reacted with olefin containing compounds.
It is an additional object of the present invention to provide an anaerobic system in which hydride-containing siloxanes are reacted with olefinic-containing polysiloxanes to produce silicone elastomers.
It is still an additional object of the present invention to provide for novel nickel complex catalysts.
It is yet an additional object of the present invention to provide a process for producing novel nickel complex catalysts.
It is still an additional object of the present invention to provide a process for forming silicone elastomers in anaerobic systems in which nickel complex catalysts are utilized to react hydrogen containing siloxanes with olefinic-containing polysiloxanes.
These and other objects of the present invention are accomplished by means of the disclosure set forth herein below.